The present invention relates to methods and compositions for the detection and treatment of a disease or condition associated with microbial antigens, more specifically to the isolation and purification of bacterial antigens, and to their use in diagnosis and treatment.
A number of idiopathic recurrent diseases are of unknown etiology. Some of these diseases are believed to be linked to infection by a microorganism, for example, a bacterium. However, the causal relationship between the microorganism and the disease is not established for many of these diseases or conditions. Even in diseases or conditions showing an association with an infectious agent, the etiology leading to the disease symptoms is generally unknown. For some diseases, such as chronic gastritis and peptic ulcer disease, and chronic inflammatory diseases of the nose and paranasal sinuses, a link is suspected between infection and allergy. The initiating event is suspected to be an infection, with allergy developing as a sequel. Subsequently, infection may exacerbate the microbial allergy which leads to both chronic hypersensitivity and chronic infection. Data in support of these theories is not capable of discriminating between them.
It has been suggested that bacterial allergy may play a significant role in chronic diseases of the aerodigestive tract. Examples of aerodigestive diseases potentially effected by bacterial hypersensitivity include asthma, nasal polyps, chronic gastritis and gastric ulcer disease. At present, no uniform view exists as to how the allergic process is mediated or, more precisely, how mast cell degranulation is induced. A bacteria-specific IgE-mediated response is postulated for some diseases in this category.
IgE-mediated reactions resulting in chronic inflammation rather than acute, short-lived reactions have been well described. The hallmark event described in these studies is mast cell degranulation. Mast cells release vasoactive mediators and late-phase reactants, such as chemotactic agents, recruit neutrophils, eosinophils, and monocytes. The influx of these cells is followed by lymphocytic infiltration. These events may become part of a chronic, repetitive process through the maintenance of a protracted mast cell degranulation.
Digestive diseases include the related disorders of chronic gastritis and peptic ulcer disease which appear to be associated with the microorganism Helicobacter pylori, but the nature of the association, and the mechanisms linking infection with subsequent symptoms are not known. Unraveling the etiology of these diseases is important because chronic gastritis and peptic ulcer disease are diseases of major significance. Five to ten percent of all individuals develop chronic gastritis and/or gastroduodenal ulcers in their lifetime. Ulcer disease is a common cause of morbidity. The annual prevalence of symptomatic peptic ulcer disease in the United States of America is approximately 18 per 1,000 adults (or about 4,500,000 people). Approximately 350,000 new cases of peptic ulcer disease are diagnosed each year.
Diagnosis of these diseases is usually performed by gastroduodenal endoscopy, an invasive and costly procedure. Treatment encompasses oral medication, dietary controls, and surgery. Rarely is treatment successful in effecting a "cure," rather these chronic conditions are characterized by cycles of improvement and relapse.
Since the report by Marshall (1983) that the bacteria Helicobacter pylori is physically associated with the lesions of chronic gastritis, a great deal of work has been done in an effort to elucidate a causal relationship between the organism and the chronic disease. Early speculations regarding localized pH changes induced by H. pylori, the release of toxins (Hupertz et al., 1988), and destructive enzymes (Slomiany et al., 1989) and the differences between different strains of the bacteria (Eaton et al., 1989) have not resulted in firm conclusions that are accepted in the art concerning the etiology of the disease (Peterson, 1991). Moreover, the search for a reasonable explanation of cause and effect has been further complicated by the recognition that a significant number of clinically well subjects also carry the presumptive infectious organism. Clearly, diagnostic tests directed solely at H. pylori would not have a suitable specificity. Therefore, for these diseases and others related to an infectious agent, new approaches are needed.
It is known that microbial proteins may be antigenic, and possibly allergenic. But there has been no systematic pursuit of a set of individual antigenic molecules that derive from a microorganism and that highlight interactions between the microorganism and a host to produce symptoms of a disease or condition.
Measurements of total immunoglobulin, even if a certain type, is a relatively crude assay because it measures a response to many antigens from many sources. Attempts to develop serological tests consisting of detecting antibodies in serum to crude extracts of bacteria have had unacceptably high false positive and false negative rates (Evans, 1989). Use of purified antigens showed some improvement. At most, assays for one antigen or allergen, or for a crude composite of antigens or allergens, are available for clinical diagnosis, but are unsatisfactory. Multivariate approaches to define a set of individual antigens specific for a microorganism, and to determine an immunological response with increased sensitivity and specificity have not been suggested.
It also is recognized that there are immunological responses of a host to the presence of a microorganism. Yet immunological profiles have not been identified heretofore that are specific for complexes between a set of individual microbial antigens and host serum antibodies which identify an organism associated with a disease or condition.